Door reinforcements serve as stiffners for automobile doors in order to absorb impact energy in the event of a lateral impact, and convert it into mechanical work which is dissipated. In this manner, passengers in a car can be protected from injury.
In the course of increasing the inherent safety of automobiles via such passive measures, reinforcement elements must be installed at certain places of the automobile body, in particular, the door of a passenger car, in order to improve the crash behavior.
A door reinforcement of this type is known from Federal Republic of Germany Paten Document OS 36 06 024. The rectangular, preferably square, hollow section, with bead portions which extend outward at both ends on the inner and outer flanges, if formed from an extruded section of light metal. That reinforcement element is formed as a load-bearing member which is fastened at both ends in the automobile door. However, this nearly square section is unsuitable for narrow body parts, such as narrow automobile doors which have a small depth available for installation and retention of the reinforcement, which may have other components which interfere with the placement of the reinforcement. It is, furthermore, difficult to adapt such a design for various structurally different automobile doors or body parts.
Another proposal for reinforcing an automobile door is present in Federal Republic of Germany Patent 31 02 328. In that structure, the door is assembled containing a load-bearing part constructed of plastic, in which an irreversibly stretchable cable extends, the ends of which are attached at the same point of articulation as the load bearing part. Thus, the cable may absorb an energy of impact by being stretched beyond its yield point.